Disable mobile theme again after updating wordpress? (2 posts)

I'm using the theme pinboard. And I wanted to disable the mobile-theme, so I removed the line: <meta name="viewport" content="width=device-width, initial-scale=1.0" /> in my header.php. And everything looked great. But when I updated my WordPress-site to 3.5.1 it turned on the mobile-theme again. But the line is'nt there. Any ideas how I could solve that and disable the mobile theme again?